Full Stack .NET Developer

Job Description

Job Description

Harmonia Holdings Group, LLC is an award-winning, rapidly growing federal government contractor committed to providing innovative, high-performing solutions to our government clients and focused on fostering a workplace that encourages growth, initiative, creativity, and employee satisfaction.

Title: Full Stack .NET Developer

Location: Washington, D.C. (Onsite)

Terms: Full-time

Clearance: Active Top Secret with SCI eligibility

Travel: 0%

Portfolio/Business Unit Context

This role supports a Department of State program focused on secure application development and mobile-enabled mission capabilities. The environment is high-security, high-visibility, supporting systems that require reliability, performance, and continuous enhancement. The work directly contributes to mission-critical operations, including secure mobility and data-driven decision support.

Position Description

Harmonia is seeking a Full Stack .NET Developer to design, build, and maintain secure, scalable applications in a classified environment. This role is suited for a developer who is comfortable working across the stack from back-end services and database design to front-end interfaces. This person needs to be able to operate effectively in a structured, security-conscious environment. The developer will be expected to write production-quality code, troubleshoot complex issues across system layers, and contribute to ongoing modernization efforts.

Responsibilities:

• Design, develop, test, and maintain full stack applications using C# and the .NET ecosystem
• Build and enhance back-end services, APIs, and data access layers
• Develop and maintain front-end components using modern web technologies (JavaScript, HTML, CSS)
• Design and optimize SQL Server databases, including stored procedures, functions, and performance tuning
• Troubleshoot and resolve issues across application, database, and infrastructure layers
• Identify and remediate security vulnerabilities in accordance with federal standards
• Support CI/CD pipelines and automated deployment processes
• Participate in Agile development processes, including sprint planning, demos, and retrospectives
• Contribute to secure mobile application support and integration efforts

Required Qualifications:

• Active Top Secret clearance with SCI eligibility (required).
• U.S. Citizenship required.
• 5+ years of professional experience in .NET/C# development
• Security+ certification.
• Strong experience building full stack applications using .NET frameworks (.NET Core, MVC, or similar)
• Proficiency with SQL Server, including T-SQL, stored procedures, and database design
• Experience troubleshooting and debugging across multiple system layers.
• Familiarity with secure development practices in regulated or classified environments.
• Experience working in Agile development teams.

Desired Qualifications:

• Experience with Azure DevOps, TFS, or similar CI/CD and build tools
• Familiarity with cloud platforms such as Azure or AWS
• Experience with version control systems (Git, TFS)
• Knowledge of SharePoint integration or development
• Exposure to secure mobile development or device management environments
• Strong problem-solving and performance tuning capabilities
• Ability to work effectively in a client-facing or mission-driven environment

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Here at Harmonia we are pleased to have been repeatedly recognized for our outstanding work culture, the innovative work we do, and the employees on our team who make a difference each day. Some of these recognitions include:

• Recognized as a Top 20 "Best Place to Work in Virginia"
• Recipient of Department of Labor's HireVets Gold Medallion
• Great Place to Work Certification for five years running
• A Virginia Chamber of Commerce Fantastic 50 company
• A Northern Virginia Technology Council Tech 100 company
• Inc. 5000 list of fastest growing companies for eleven years
• Two-time SBA SBIR Tibbett's Award winner
• Virginia Values Veterans (V3) Certification

We recognize that every bit of our success is the result of our teams of hard-working, motivated, and innovative professionals who are proud to call themselves part of the Harmonia family! In addition to competitive compensation, a family-focused culture, and a dynamic, productive work environment, we offer all full-time employees a variety of benefits including, but not limited to

• Traditional and HSA- eligible medical insurance plans
• 100% employer-paid dental and vision insurance options
• 100% employer-sponsored STD, LTD, and life insurance
• 5% 401(k) company matching
• Flexible-schedules and teleworking options
• Paid holidays and PTO Accrual Plans
• Paid Parental Leave
• Professional development and career growth opportunities
• Team and company-wide events, recognition, and appreciation-- and so much more!

Check out our LinkedIn, Facebook, and Instagram to find out a little more about who we are and if we are the right next step for your career!

Harmonia is an Equal Opportunity Employer providing equal employment opportunity to all employees and applicants for employment without regard to race, color, religion, national origin, age, gender, gender identity, sexual orientation, disability, or genetics. Harmonia does and will take affirmative action to employ and advance in employment individuals with disabilities and protected veterans. To perform the above job successfully, an individual must possess the knowledge, skills, and abilities listed; meet the education and work experience required; and must be able to perform each essential duty and responsibility satisfactorily. Other duties in addition to those listed may be assigned as necessary to meet business needs. Reasonable accommodation will be made to enable an applicant with a disability to successfully apply for and/or perform the essential duties of the job. If you are in need of an accommodation, please contact HR@harmonia.com.